Loud Metal Bang

[Cammaxon]

Soooo confused. Drained the oil, clean.
car would NOT boost at all after picking it up, but it also would NOT make the loud metal bang we heard several times on the dyno.

Checked all the vacuum lines, checked for leaks ect none. pulled the turbo. Will not spin at all if there is pressure on it. Was feeding the turbo from the oil filter housing with a restrictor. Was not pushing oil at all.

put my 20g back on using the same lines i had the scm6152 hooked up with, again from the oil filter housing. runs fine boosts hard no loud metal bang.

only question? why/how could the bang have been from the turbo? maybe unsticking its self?